Heat storing hair roller

ABSTRACT

A heat storing hair roller is provided having an outer plastic casing and an inner heat storage body filled with a heat storage material. Means, such as a plurality of radially directed protrusions, are provided between the plastic casing and the inner body in order to impart a radial stress on the plastic casing. This radial stress compensates for the greater thermal expansion rate of the plastic casing as compared to the inner heat storage body and maintains good thermal contact between the casing and the storage body despite the difference in thermal expansion rate.

Jensen [54] HEAT STORING HAIR ROLLER [72] Inventor: Erik Kjaer Jensen, Kalundborg,

Denmark [73] Assignee: Bristol-Myers Company, New York,

[22] Filed: Feb. 1, 1971 [21] Appl.No.: 111,539

[30] Foreign Application Priority Data March 3, 1970 Denmark ..1053/70 [52] US. Cl. ..132/33 R [51] Int. Cl. ..A45d 2/12 [58] Field of Search ..132/40, 38, 39, 41, 44, 33 R, 132/46 [56] References Cited UNITED STATES PATENTS 3,559,658 2/1971 Genest ..132/33 3,581,055 5/1971 Makino ..132/33 R [15] 3,696,819 51 Oct. 10,1972

9/1970 Abe ..132/40 10/1969 Block et a1. ..132/33 R Primary Examiner-Louis G. Mancene Assistant Examiner-Gregory E. McNeil] Attorney-William F. Moss, 111, David J. Mugford, Irving Holtzman, George A. Mentis, Ralph D. Gelling and Marvin B. Rosenberg s7 ABSTRACT 11 Claims, 4 Drawing Figures 1 HEAT STORING HAIR ROLLER BACKGROUND OF THE INVENTION Recently, hair rollers had been provided having a heat storage body encased in a plastic outer housing. In such hair rollers the difference between the coefficient of thermal expansion between the heat storage body and the outer plastic housing has resulted in at least partial separation of the heat storage body and the outer plastic housing when the rollers are heated. Such separation causes poor heat conducting contact between these two members. As a consequence, with conventional rollers it was necessary for the inner heat storage body to be heated to higher temperatures than would otherwise be necessary merely to reach proper operating temperatures on the roller surface. Moreover, even despite the higher temperatures employed, heat transmission from the heat storage body through the plastic casing to the hair wound on the rollers was inefficient, thereby reducing the overall effectiveness of the hair rollers.

As a further consequence, with the conventional rollers, it was possible for the outer plastic casing to become completely separated from the inner heat storage body so that the outer plastic casing could be drawn loose from the heat storage body when the hair roller was removed from its heating mechanism.

STATEMENT OF THE INVENTION This invention overcomes the drawbacks of such hair rollers and provides improved heat conducting contact between the outer casing and the heat storage body in heated hair rollers. The hair roller of the invention provides improved heat transfer and more secure attachment between the inner heat storage body and the outer casing. This is accomplished in a heat storage roller having an outer casing and an inner heat storage body by the provision of means disposed between the heat storage body and the outer casing adapted to exert an outward force against the outer casing so as to create a radial or outward stress therein. When the roller is heated, the stress is relieved as the outer casing expands. The relieving of the stress in this manner compensates for the difference in thermal expansion rate between outer casing and the heat storage body and insures good heat conducting contact between the inner heat storage body and the outer casing.

GENERAL DESCRIPTION OF THE INVENTION The invention is described herein with particular reference to a hair roller in which the outer casing is made of a plastic material which is to an extent deformable and preferably which is of a thermoplastic material. However, this invention is applicable to any hair roller having an inner heat storage body and an outer casing wherein the outer casing has a greater coefficient of thermal expansion than the heat storage body. This invention has particular application to hair rollers of the type shown in US. Pat. No. 3,410,985 to Giacchero which discloses a hair roller having an inner casing 14 housed within a plastic outer casing 20.

This invention provides means preferably to radially deform the outer casing. Such means can be in the form of projections directed inwardly from the outer casing or protrusions directed outwardly from the inner heat storage body. The projections or protrusions are of such dimensions that they impart a force from the inner heat storage body toward the outer casing so as to slightly deform the wall of the outer casing thereby subjecting the casing to an outward stress. Thus, when the plastic outer casing is heated and the heat expands the casing, the first effect of the expansion will be to relieve the stress and compensate for the elastic deformation of the casing wall. This, however, will not disturb the thermal contact between the outer casing and the heat storage body via the projections or protrusions. This contact between the projections and the heat storage body provides sufficient heat conduction to the outer casing, and the thermal contact between the outer casing and the inner casing is maintained.

The projections or protrusions referred to above can be in the form of a plurality of longitudinal ribs or ridges formed on the inner surface of the outer plastic casing. However, they could be a series of projecting dimples or tabs or any other series of projections of uniform size. A single helical rib could, for example, also be used. Furthermore, combinations of different types of projections can be used. The projections or protrusions need not be formed on the inner surface of the outer casing. It is possible, if desired, to form them on the outer surface of the inner heat storage body. Such projections or protrusions will apply force to the outer casing in the same manner as if they had been formed on the inner surface of the outer casing. As an additional possibility, the means for imparting a radial or outward stress to the outer casing could comprise separate member such as a straight or helical strip which is inserted between the inner heat storage body and the outer plastic casing.

It is preferred that whether the projections are formed on the inner casing, the outer casing, or as separate elements, that they be formed as strip-like members which deform the outer casing into a generally polygonal outer cross-sectional shape. As a result of the deformation of the outer casing when it is mounted on the inner casing when the outer casing is heated and expands it will assume substantially circular cross-sectional shape. However, efficient heat conducting contact with the inner heat storage body through the inwardly directed projections will be maintained. Moreover, as a result of the polygonal cross-sectional shape as described above, when the outer casing is cold, the outer surface of the inner heat storage body and the inner surface of the outer plastic casing will be very close to each other and can touch each other at the positions between the projections where each side of the polygonal outer casing is tangent to the inner cylindrical heat storage body. This provides rapid heat up of the plastic casing.

The construction described above provides substantially improved and uniform heat transmission from the inner heat storage body to the outer casing as compared to conventional hair rollers wherein immediately upon heating, the inner storage body loses contact with the plastic casing. In such conventional hair rollers there is a rapid expansion of the outer casing and irregular heat conduction to the outer casing. By means of the projections, or other means provided to maintain the stress between the outer casing and the inner heat storage body, the plastic casing is retained in position by frictional contact and this prevents the outer casing from being axially displaced from the inner heat storage body. Furthermore, the outer casing and the heat storage body can be held together by providing corresponding depressions to the projections so that at least one projection engages a corresponding groove in the adjacent facing surface. This can be done, for example, by providing a circumferential rib on the inner surface of the plastic casing which engages a corresponding circumferential groove formed on the outer surface of the heat storage body.

Hair rollers of the type referred to herein often have a heat storage body formed in an annular cross-sectional shape and comprise a double walled tubular container which is open at one end and between the walls of which the heat storage material is enclosed. An annular plug may be introduced into the open end of this tubular walled container. The plug normally has a bore through the center thereof of sufficient size to admit a heating post or support pin. The annular plug aids in providing good contact between the plastic casing and the inner heat storage body. This is particularly the case when the annular plug is bonded to the plastic casing for example by plastic welding.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of the outer casing of the hair roller of the invention.

FIG. 2 is a cross-sectional view of the outer plastic casing of the invention taken along the line ll II of FIG. 1.

FIG. 3 is a view similar to FIG. 2 showing the heat storage body in position inside of the outer plastic casmg.

FIG. 4 is a view in cross-section and partially broken away of the open end of the hair roller of the invention.

The cylindrical outer plastic casing 1 shown in FIG. 1 is made of polypropylene and has a series of longitudinal rows of spines 2 on the exterior surface thereof for holding hair wound thereon in position. The spines are positioned in each row such that the spines of the neighboring row are longitudinally offset by one half the distance between the spines. This can be seen by reference to FIG. 1. The plastic casing l is shaped as a cylinder which is closed at one end. The inner surface is formed with a series of projections in the form of ribs 4. The ribs 4 are uniformly spaced apart over the inner circumferential surface and are directed radially inwardly toward the center of the cavity inside the outer casing. The ribs extend longitudinally from the end plate 3 over a substantial portion of the length of the casing. Adjacent to the open end of the plastic casing an annular segmented rib 5 is formed around the inside surface of the casing 1. As can be seen by reference to FIG. 1, this annular rib is perpendicular to the longitudinal ribs 4 formed on the inner surface of the casing.

The heat storage body, which can be seen in FIG. 4, is made of aluminum and comprises a double walled tubular container which is adapted to retain a heat storage substance 18 such as erythrite between the walls thereof.

The plastic casing l, as seen in FIG. 2, when it is not positioned about the heat storage body 6 is circular in cross-section. When the casing, however, is assembled onto the heat storage body 6, the force applied by means of the ribs 4 slightly deforms the casing and it assumes a polygonal cross-sectional shape as can be seen by reference to FIG. 3. The force applied by the ribs 4 also creates a stress in the casing 1 and tightly holds the casing against the inner heat storage body 6. When the hair roller is heated to its operating temperature the plastic casing, which has a high coefficient of thermal expansion as compared to the inner body 6, expands to a greater extent than the inner body. The outer casing expands, the outwardly directed force or stress is relieved and the casing assumes a circular cross-sectional shape. Nevertheless, the casing remains in efficient heat conducting contact with the inner heat storage body as a result of the thermal contact between the heat storage body 6 and the ribs 4. This heat conducting contact remains despite the fact that the outer casing expands to a greater extent than the heat storage body. This is a result of the fact that for the operating temperatures of the heat storage body, the outer casing does not expand sufficiently to both relieve the stress in the outer casing, and still expand further to loosen the contact between the ribs and the heat storage body. This is in contrast to the known type of hair roller in which as soon as any significant expansion occurs, efficient heat conducting contact between the roller casing and the heat storage body is lost.

As noted above, axial displacement of the outer casing relative to the inner heat storage body is prevented due to the frictional engagement of the ribs against the inner body 6. In the embodiment shown the circumferential rib 5 on the inner surface of the plastic casing 1 also aids in preventing relative axial displacement of the inner body with relation to the casing. The rib 5 as is shown in FIG. 4 engages a circumferential groove 7 in the heat storage body 6. The rib 5 aids in providing heat conducting contact during the initial stages of heating. If desired, a plurality of such corresponding ribs and grooves may be employed. If, as suggested above, the projections are formed on the heat storage body, or are separate members, ridges or depressions can, as an alternative construction, be provided in the inner surface of the outer plastic casing to aid in preventing relative displacement of the two members.

In the embodiment shown in FIG. 4, an annular plug is fitted into the end of the plastic casing 1. This annular plug 8 contacts both the plastic casing and the heated storage body 6. The annular plug 8 is formed with a flange 10 which engages a corresponding flange 12 on the bottom of the heat storage body so as to lock the two members together. Plug 8 has a central opening 14 of sufficient size to accommodate a heating pin or support post for the hair roller and this support post fits into the central cavity 16 of the tubular heat storage body 6. The plug 8 can be secured to the casing l by any form of bonding such as by ultrasonic welding, plastic melt welding or by resin or solvent bonding. The plug further improves the heat conducting contact between the inner heat storage body and the plastic casing and also prevents the fingers of the user from contacting the inner heat storage body.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable embodiments thereof:

1. A heat storing hair roller comprising, in combination, an outer casing, a heat storage body positioned within said outer casing, and means positioned between said heat storage body and said outer casing said means exerting a force between said heat storage body and said outer casing and imparting an outwardly directed stress on said outer casing so as to maintain thermal contact between said heat storage body and said outer casing despite any differential thermal expansion therebetween.

2. A hair roller in accordance with claim 1 in which said means comprises a plurality of inwardly directed projections formed on the inner surface of said outer casing.

3. A hair roller in accordance with claim 2 in which said projections comprise a plurality of ribs uniformly spaced over the inner circumferential surface of said outer casing and extending longitudinally of said outer casing.

4. A hair roller in accordance with claim 1 in which said outer casing is formed of a plastic material.

5. A hair roller in accordance with claim 1 in which said means imparts a sufficient stress on said outer casing to deform it.

6. A hair roller in accordance with claim 5 in which said means includes circumferentially spaced projections to deform said outer casing into a substantially polygonal cross-sectional shape.

7. A hair roller in accordance with claim 1 including a projection formed on the inner surface of said outer casing; and a depression corresponding to said projection formed on the outer surface of said heat storage body, said depression and said projection cooperating to prevent axial displacement of said heat storage body relative to said outer casing.

8. A hair roller in accordance with claim 7 in which said projection comprises a circumferential rib, and in which said depression comprises a corresponding groove.

9. A hair roller in accordance with claim 1 in which said heat storage body comprises a tubular doublewalled container closed at one end, and having a heat storage material therein; said outer casing comprising a tubular container for said heat storage body closed at one end, and said outer casing having a plurality of spines formed on the outer surface thereof.

10. A hair roller in accordance with claim 9 in which said outer casing and said heat storage body are each formed with an open end and in which a plug engages both the open ends of said outer casing and said heat storage body, said plug having a central aperture therein to permit entry of a heating member into the central passage of said tubular heat storage body.

11. A hair roller in accordance with claim 10 in which said plug is bonded in position. 

1. A heat storing hair roller comprising, in combination, an outer casing, a heat storage body positioned within said outer casing, and means positioned between said heat storage body and said outer casing said means exerting a force between said heat storage body and said outer casing and imparting an outwardly directed stress on said outer casing so as to maintain thermal contact between said heat storage body and said outer casing despite any differential thermal expansion therebetween.
 2. A hair roller in accordance with claim 1 in which said means comprises a plurality of inwardly directed projections formed on the inner surface of said outer casing.
 3. A hair roller in accordance with claim 2 in which said projections comprise a plurality of ribs uniformly spaced over the inner circumferential surface of said outer casing and extending longitudinally of said outer casing.
 4. A hair roller in accordance with claim 1 in which said outer casing is formed of a plastic material.
 5. A hair roller in accordance with claim 1 in which said means imparts a sufficient stress on said outer casing to deform it.
 6. A hair roller in accordance with claim 5 in which said means includes circumferentially spaced projections to deform said outer casing into a substantially polygonal cross-sectional shape.
 7. A hair roller in accordance with claim 1 including a projection formed on the inner surface of said outer casing; and a depressiOn corresponding to said projection formed on the outer surface of said heat storage body, said depression and said projection cooperating to prevent axial displacement of said heat storage body relative to said outer casing.
 8. A hair roller in accordance with claim 7 in which said projection comprises a circumferential rib, and in which said depression comprises a corresponding groove.
 9. A hair roller in accordance with claim 1 in which said heat storage body comprises a tubular double-walled container closed at one end, and having a heat storage material therein; said outer casing comprising a tubular container for said heat storage body closed at one end, and said outer casing having a plurality of spines formed on the outer surface thereof.
 10. A hair roller in accordance with claim 9 in which said outer casing and said heat storage body are each formed with an open end and in which a plug engages both the open ends of said outer casing and said heat storage body, said plug having a central aperture therein to permit entry of a heating member into the central passage of said tubular heat storage body.
 11. A hair roller in accordance with claim 10 in which said plug is bonded in position. 